This invention relates to an oven hood-equipped high-frequency heating apparatus which has the function of exhausting gas generated from other heating cooking device installed below an apparatus body, and is of such a construction that an exhaust opening cover, provided at an exhaust opening for discharging the generated gas from the apparatus body, is automatically opened and closed by driving a motor.
A conventional exhaust opening cover can be automatically opened and closed to secure a high degree of opening when it becomes necessary to ventilate a room by a ventilation fan or when it becomes necessary to secure an intake opening so as to cool a heating part during the operation of a high-frequency heating apparatus. In addition, in an inoperative condition, such a conventional exhaust opening cover is held in a closed condition to assume a flat appearance, so that the design can be enhanced, and also the intrusion of dust and dirt can be prevented (see, for example, U. S. Pat. No. 6,335,521).
For example, the opening and closing of most of such exhaust opening covers have been effected only by mechanical means utilizing the operation of a stepping motor which can limit its rotating direction.
FIGS. 3A and 3B show the opening and closing of an exhaust opening cover of a conventional apparatus.
The conventional apparatus includes an exhaust opening cover 1, a motor 2 for automatically opening and closing the cover, a cam 3 for converting the rotation of a motor shaft into a moment, a boss 3-a formed on the cam so as to transmit power to a part connected to the cam, a part 4 (constituting the exhaust opening cover) for receiving the rotational movement of the cam, a slit 4-a which is formed in the exhaust opening cover-constituting part, and is connected to the boss formed on the cam, and a rotation shaft 5 of the exhaust opening cover, an exhaust opening portion 6, and a draft 7 of exhaust discharged from the apparatus.
In the above conventional construction, however, the exhaust opening cover portion and the motor shaft portion are integrally interconnected, and the driving force of the motor is all applied to one point, that is, to the boss formed on the cam. Therefore, an undue stress develops in a force-transmitting direction, and the durability of the interconnecting moving portions is adversely affected, so that it has been difficult to secure the reliability. And besides, since the stepping (rotational direction-limiting) motor is used for the exhaust opening cover, it has been difficult to secure the quality of the motor. Furthermore, when the exhaust opening cover is forcibly opened and closed by applying a force to the exhaust opening cover from the exterior, this force is transmitted as an overload directly to the motor because of the integrally-interconnecting construction, and this leads to a factor in malfunction of the motor. Thus, these problems, relating to the product quality, have been encountered.